Pneumatic supply-exhaust circuit



United States Patent [72] Inventor Joseph E. Hogel OTHER REFERENCESRiver Grove, Illinois R. E. Norwood, and M. R. Noll, Shift Register with[21] AppLNo. 808,268 Pneumatically Controlled Latch and ControlElements" [22] Filed March 18, 1969 in I.B.M. Technical DisclosureBulletin. vol. 7, No. 4, Sep. [45] Patented Nov. 17, 1970 1964, pp. 29799. [73] Assignee Honeywell Inc., M. R. Noll, and R. E. Norwood,Pneumatically-Con- Minneapolis, Minnesota a corporation of Delaware [54]PNEUMATIC SUPPLY-EXHAUST CIRCUIT 12 Claims, 2 Drawing Figs.

52 u.s.c1. 137/608,

235/201 511 1111.61 F15c3/04 so Fieldoi'Seai'ch 137/561,

608: 235/(Consulted), 200, 201

trolled Logic Circuits" in I.B.M. Technical Disclosure Bulletin, vol. 7,No. 4, Sep. 1964, pp. 295-96.

Primary EXaminerWilliam R. Cline Attorneys- Lamont B. Koontz, Francis A.Sirr and John S.

Sumners PNEUMATIC SUPPLY-EXHAUST crncurr The invention disclosed anddescribed is a pneumatic logic circuit that performs a supply-exhaustfunction. While this function'is generally provided by apneumatic relaythat em- -The supply-exhaust output characteristic corresponding toeither an increasing or decreasing variable input pressureordinarily'consists of (a) supplying pressure to an outlet; (b)

" maintaining constant pressure at the outlet; and (c)exhausting-pressure from the outlet. The pneumatic logic circuitaccomplishes this with two groups of diaphragm valves, the first ofwhich performs functions (a) and (c) by supplying pressure to orexhausting pressure from a pressure line in response to the variableinput pressure. The second group of valves performs functionlb) bycontrolling the communication of pressure in the line to the outlet inresponse to the variable input pressure.

Because of the nature of small diaphragm valves, all of the pneumaticcircuit components can be formed in a single integrated member,resulting in a small, reliable unit that operateswith a minimum ofmoving parts.

BRIEF DESCRIPTION or THE DRAWING FlG. 1 is a schematic representation ofa pneumatic logic circuit that performs a supply-exhaust function.

FIG. 2 is a truth table indicating operation of the pneumaticlo'giccircuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS i The pneumatic'logic circuitdisclosed in FIG. 1 consists of "seven pressure responsive valves 31-37,each of which has a control chambcr'4l, an inlet chamber 42, an outletchamber 4'3, a diaphragm 44 and an annular ridge upon which {diaphragm44 seats. Numbers 4145 are shown only with frespect to valve 31, butlike numbers apply to each of the other valves 32--37. When pressureadmitted to control chamber 41, is great enough, diaphragm 44 seats onridge 45 and prevents the communication of pressure between chamf'bers'42 and 43.

Control chambers 41 of diaphragm valves 31 and 32 are adapted forconnection with a variable input pressure by means of a conduit 29.

lnlet chamber 42 of diaphragm valve 31 receives a supply of cregulatedpressure from a source 46 through a conduit 61 that "includes arestriction 51. Conduit 61 is further connected to the control chamber41 of diaphragm valves 33 and 34. A condu'it'62 including a restriction52 allows the pressure in outlet "chamber 43 of diaphragm valve 31 to bevented to at- 'mosphere.

The inlet chamber 42 of valve 32 receives a supply of regu- "latedpressure from a source 47 through a conduit 63 having a "restriction.53. Outlet chamber 43 of valve 32 is connected to the control pressurechamber 41 of valve 35 by a conduit 64, which is vented to atmospherethrough a restriction 54,

A'source 48 supplies regulated pressure through a restric- Regulatedpressure supply48 is also connected, through a restriction S7, to theinlet chamber 42 of valve 33, and through aconduit 71 to the controlchamber41 of valve 36,

Regulated pressure from a source 49 passes through a "restriction 59 anda conduit 72 to the inlet chamber 42 of -valve 36. 'Conduit 72 includesa variable restriction 80 up- 'streamoffits connection to inlet chamber42 of diaphragm valve 37. Outlet chamber 43 of valve 36 communicatesdirectly with atmosphere through a conduit 73, while conduit 30, whichserves as the circuit output, is connected to the outlet chamber 43 ofdiaphragm valve 37. i

An alternative method of describing the interconnection of diaphragmvalves and pressure sources is to the effect that the inlet chambers 42of valves 31-36 are each adaptedforco'nnection with a restricted sourceof fluid pressure; the outlet chambers 43 of valves 3134 eachcommunicate with atmosphere through a fluid restriction; the outletchambers 43 of valves 35 and 36 each communicate directlywith'atmosphere; the control chambers 41 of valves 31 and 32 are adaptedfor connection with a variable pressure; conduit 61 connects inletchamber 42 of valve 31 with control chambers I 41 of valves 33 and 34;conduit 64 connects the outlet chamber 43 of valve 32 with the controlchamber 41 of valve 35; conduit 71 connects the inlet chamber 42 ofvalve 33 with the control chamber 41 of valve 36; conduit 65 connectsthe inlet chambers 42 of valves 34 and 35 with the control chamber 41 ofvalve 37; conduit 72, which includes variable restriction 80, connectsthe inlet chamber 42 of valve 36 with the inlet chamber 42 of valve 37;and conduit 30, which is connected to the outlet chamber 43 of valve 37,serves as the circuit outlet.

Functionally, operation of the pneumatic circuit can be analyzedbyobserving the valve groupings as represented by the dotted lines ofFIG. 1, One group falls within the area en closed by a dotted line 11and includes valves 31, 33 and 36. The other group is bounded by adotted line 12 and includes valves 31, 32, 34, 35 and 37. Because theoperation of valve 31 affects the operation of both valves 33 and 34,which are in separate groups, valve 31 is considered to be in bothgroups.

If it is assumed that the variable input pressure has an overallpressure range that can be broken down into first, second andthirdpressure ranges which increase pressurewise in the stated order,then it can be stated that the broad function of the first group ofvalves is to provide an output pressure in conduit72 of a first order ofmagnitude in response to the variable input pressure in the first range,and an output pressure of a second order of magnitude in response to thevariable input pressure in the second and third ranges.

Specifically, this function is accomplished in part by relating theparameters of diaphragm valve 31 so that its diaphragm 44 seals theannular ridge 45 when the variable input pressure passes from the firstto the second operating range. When this happens the pressure in conduit61, which was previously bled to atmosphere through conduit 62 andrestriction S2, begins to build up until the diaphragm 44 of valve 33closes on its associated annular ridge 45. This causes a similar buildup of pressure in conduit 71, causing valve 36 to close. The pressure inconduit 72 begins to increase by virtue of its connection with pressuresource 49, thus resulting in an output pressure of a second order ofmagnitude" that corresponds to the variable input pressure in the secondrange.

With the variable input pressure in the first range, valves 31, 33 and36 are all open by virtue of the pressure in the respective chambers 41being less than the pressure in the respective chambers 42, resulting inthe exhausting of pressure in conduit 72 to atmosphere through conduit73. First order of magnitude therefore describes the output pressure inconduit 72 in a decreasing or exhausting state.

Broadly speaking, the function of the valves in the second group withrespect to the variable input pressure is to receive the output pressurefrom the first group of valves and allow passage of that pressure to apressure outlet when the variable input pressure is in the first andthird ranges, and to preclude passage when the variable input pressureis in the second range.

The accomplishment of this function can be better understood by breakingthe valves of group two (dotted line 12) into a firstsubgroup includingvalves 31 and 34, a second subgroup including valves 32 and 35 and athird subgroup including valve 37.

, 3 'For-the first subgroup, a variable input pressure in the firstrange allows valve 3i to open, therebyallowing the pressure in conduit61 to bleed down and allow valve 34 to open. Therefore, when thevariable input pressure is in the'first range valve '34 allowsthe'pressure in Conduit 65 to be exhausted through conduit67andrestriction 56. When the variable input pressurereaches the secondrange, valves 31 and 34 close so that pressure in conduit 65 cannotescape through conduit 67 and restriction 56.

With respect to the operation of the second subgroup of valves, theparameters for valve 32 are chosen so that it is open when the variableinput pressure in conduit 29 is in the first and second ranges, and isclosed when the variable input pressure isin the third range. With valve32 open, the pressure in conduit 64 builds up (the resistance value ofrestriction 53 is lessthan that of restriction 54), and valve 35 closesto prevent the venting of pressure to atmosphere through connduit 68.When the variable input pressure is in the third range valve 32 isclosed, and valve 35 opens due to the loss of pressure in its controlchamber 41 through restriction 54. The

pressure in conduit 65 is therefore exhausted to atmospherethroughconduit' 68.

The pressure in conduit 65 determines whether the third subgroup-valve37 is opened or closed. From the foregoing discussion, it is evidentthat there are three possible operating combinations for the. valves 34and 35-b0th closed, and alternative positions of one open and oneclosed. Because of the venting conduits 67 and 68, the only combinationthat will allow pressure iniconduit 65 to build up and close valve 37 iswith both valves 34 and 35 closed. This occurs only when the variableinput pressure is in its second range, the pressure in conduit 65 beingexhausted through conduits 67, 68 under all other conditions. g

, Broadly resta ting the overall function, the first valve groupexhausts pressure from conduits 72 when the variableinput pre'ssure'isin the'first range, and adds pressure to conduit 72 when the variableinput pressure is in the second and third ranges. The second valve groupreceives the pressure in conduit 72 and allows it to pass to thepressure outlet 30 when the variable input signal is in the first andthird ranges, anti blocks the outlet when the variable input pressure isin the second range.

Because valve 37 blocks the communication of pressure between conduit 72and conduit 30 when the input pressure is in'the second ra'ngeQthe stateof pressure in conduit 72 as generated by thefirst group of valves inresponse to the input pressure in that range is unimportant. in thepreferred embodiment this pressure is of the second order of magnitude,or

. in the increasingstate.

I A typical operating range for the variable input pressure is l6 p.s.i.For such a range, theparameters relating to diaphragm 3l-canbe chosen sothat the valve closes when the input pressure in conduit 29 is 3 p.s.i.or greater. Similarly, diaphragm 32 can be designed to close at 4 p.s.i.or greater.

FIG. 2 is a truth table showing operation of the valves 31- --37 for thegiven ranges of input pressure (P,), and the resulting output pressure(P,,). For the 0-16 p.s.i. range, the first range" is 0-3 p.s.i., thesecond rangeis 34 p.s.i. and the "third range is 4-l6 p.s.i. With theseranges, operation of the pneumatic-logic circuit can be deduced from theforegoing discussion coupled with the truth table of FIG. 2, in which 0"and C" refer to the open-or closed position of each respective valve.FIG. 1 discloses the position of the valves 3l-37'for an input pressurein the third range; i.0., P, is greater than 4 p.s.i.

I claim: x 1. Apparatus for providing an output pressure of a desiredcharacteristic in response to a variable input pressure having a first,second and third range, comprising:

first pressure responsive means for providing a first pressurev ofafirst order of magnitude in response to the-inputp'res-' sure in thefirst range, and a first pressure of a second order of magnitude inresponse to the input pressure in the third range; and a second pressureresponsive means responsive to the" input pressure for controlling thepassage of the first pressure to a pressure outlet, the second meansallowing passage when the input pressure is in the first and third'ranges,

and precluding passage when the input pressure is in the second range.

2, The apparatus as defined by claim 1, wherein the first 5 meansprovides a first pressure ofa second order of magnitude in response tothe input pressure in the second range.

3. The apparatus as defined by claim 1, wherein the second pressureresponsive means comprises:

third pressure responsive means for providing a second pressure of afirst order of magnitude in response to the input pressure in the firstrange, and a second pressureof a second order of magnitude in responseto the input pressure in the second and third ranges;

fourth pressure responsive means for providing a third pressure ofathird order of magnitude in response to the input pressure in the firstand second ranges, and a thirdpressure of a second order of magnitude inresponse to the input pressure in the third range; and v fifth pressureresponsive range for controlling passage ofthe first pressure to thepressure outlet, the fifth pressure responsive means responsive to thesecond and third pressures and arranged to preclude passage when thesecond and third pressures are in their second and first orders ofmagnitude, respectively, and to allow passage for all other second andthird pressure combinations.

4. The apparatus as defined by claim 3, wherein the third pressureresponsive means comprises:

first and second valve means each of which has an inlet, and outlet,a-pre'ssureresponsive member movable between an open position and aclosed position to establish or preclude communication between the inletand outlet and a control'input communicating with the pressureresponsive member;

the inlets of thefirst and second valve means adapted for connection toa restricted supply offluid pressure;

the outlets ofthe first and second valve means communicating withatmosphere through a fluid restriction;

first conduit means connecting the inlet of the first valve means withthe control input of the second valve means; and

second conduit means connecting the inlet ofthe second valve means withthe fifth pressure responsive means.

5. The apparatus as defined by claim 3, wherein the fourth pressureresponsive means comprises;

third and fourth valve means each of which has an inlet, an outlet, apressure responsive member movable between an open position and a closedposition to establish or preclude communication between the inlet andoutlet and a control input communicating with the pressure respon-- sivemember; the inlets of the third and fourth valve means adapted forconnection to a restricted supply of fluid pressure;

the outlet of the third valve means communicating with atmospherethrough a fluid restriction; the outletofthe fourth valve meanscommunicating directly with atmosphere;

third conduit means connecting the outlet of the third valve.

pressure responsive means comprises:

'a fifth valve means having'an inlet, an outlet, a pressureresponsivomemher movable between an open position and a closed positiontoestablish or preclude communication between the inlet and outlet and acontrol input communicating with the pressure responsive means;

the control"input of the fifth valve means arranged to receive thesecond and third pressures;

the inlet of the fifth valve means urranged'to receive the firstpressure; and

the outlet ofthe fifth valve means serving as the pressure outlet forthe apparatus.

7. The apparatusas defined by claim 1, and further comprising throttlingmeans disposed between the first and second pressure responsive meansfor restricting the flow of fluid toward and away from the pressureoutlet.

8. A pneumatic circuit comprising:

first, second, third, fourth, fifth, sixth and seventh valve means, eachof which has an inlet, an outlet, a pressure responsive-member movablebetween an open position and a closed position to establish or precludecommunication between the inlet and outlet and a control inputcommunicating with the pressure responsive means;

the inlets of the first, second, third, fourth, sixth and seventh valvemeans adapted for connection with a restricted supply'of fluid pressure;

theoutlets ofthe first, second, third and sixth valve means constructedand arranged to be moved when the variable 4 valve means; 7

second conduit means connecting the inlet of the second valvcj meanswith the control input of the fifth valve means;

third conduit means connecting the outlet of the third valve means withthe control input ofthc fourth valve means; fourth conduit meansconnecting the inlet of thefourth valve means with the control input ofthe fifth valve mcans;. fifth conduit means connecting the inlet of thesixth valve means with the control input of the seventh valve means;sixth conduit means connecting the inlet of the seventh valve means withthe inlet of the fifth valve means; and the outlet of the fifth valvemeans serving as the circuit outlet.

9. The pneumatic circuit as defined by claim 8, wherein the movablemembers of the respective valve means are each moved from the openposition to the closed position in response to increasing variablepressure.

10. The pneumatic circuit as defined by claim 9, wherein the respectivevalve means each comprises:

a housing;

diaphragm means dividing the housing into first and secondpressurechambers;

ridge means disposed in the second pressure chamber and arranged tooperate in scalable relation with the. diaphragm means to further definean inlet pressure chamber and an outlet pressure chamber within thesecond pressure chamber; the control input communicating with the firstpressure chamber; the inlet communicating with the inlet pressurechamber;

and the outlet communicating with the outlet pressure chamber. ll. Thepneumatic circuit as defined by claim 9, wherein the first value atwhich the first valve means closes is less than the second value atwhich the third valve means closes.

12 The pneumatic circuit as defined by claim 8, and further comprisingafluid restriction disposed in the sixth conduit means.

